640242641 has 4 divisors (see below), whose sum is σ = 650738484. Its totient is φ = 629746800.

The previous prime is 640242637. The next prime is 640242653. The reversal of 640242641 is 146242046.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 31584400 + 608658241 = 5620^2 + 24671^2 .

It is a cyclic number.

It is not a de Polignac number, because 640242641 - 2² = 640242637 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640242671) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5247830 + ... + 5247951.

It is an arithmetic number, because the mean of its divisors is an integer number (162684621).

Almost surely, 2^640242641 is an apocalyptic number.

640242641 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

640242641 is a deficient number, since it is larger than the sum of its proper divisors (10495843).

640242641 is a wasteful number, since it uses less digits than its factorization.

640242641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10495842.

The product of its (nonzero) digits is 9216, while the sum is 29.

The square root of 640242641 is about 25303.0164407329. The cubic root of 640242641 is about 861.8827693749.

Adding to 640242641 its reverse (146242046), we get a palindrome (786484687).

The spelling of 640242641 in words is "six hundred forty million, two hundred forty-two thousand, six hundred forty-one".